What I experienced was during rapid ( 1 per second) or full 8.3 frames per/sec for 10 frames or so. that I would get a Card failure error message and the camera would freeze up to the point that I would have to remove the battery to re boot the camera (canon 1d mkII). When I got home I would have to manually down load the files a small group at a time until I found the the files that were corrupt delete those files and down load the rest. I have formatted and defragged them on the computer (surface scan) then put them in the camera and reformatted them in the camera. I have never had this problem with a card only with the micro-drives. I do not the the drives any more they were green 2.2 gig (ultra store) maybe. It had occurred with all firmware upgrades of my camera.